刹车油GC-MS分析及在案件中的应用

Application of GC-MS into Determining the Brake Fluid for a Case

刹车油是液压制动系统中传递制动压力的液态介质,常用的有醇醚型和酯型刹车油。在一起损坏刹车油管意图谋杀的案件中,刹车油的分析对关联作案工具至关重要。本文建立了GC-MS分析刹车油的方法,通过对醇醚类物质裂解机制的推断,确定了特征离子,实现了微量刹车油的检测。结合金属成分分析结果,在案件中为确定作案工具提供了关键证据。一方面为类似案件中刹车油成分分析提供技术参考,另一方面希望能帮助办案人员树立起利用微量物证的意识和观念,为案件的分析和现场重建提供新思路。

Brake fluid is a liquid medium that fills in the hydraulic pressure-conveying system for one relevant mechanical equipment(e.g.,an automobile)to halt through its transmitted braking force.The most commonly-used brake fluid is alcohol ether and/or ester.In a case of suspected murder from the involving minibus that was damaged of its brake tubes,analysis of the brake fluid was becoming the key to determine the criminal tool.Yet,no previous report and/or literature was found about such a forensic analysis.GC-MS was tried to analyze the brake fluid,having a critical organic substance(tetra-ethylene glycol monobutyl ether)identified from the damaged brake tube and verified through the criminal tool.With combination of the analytic results of metal evidence from SEM-EDS,the criminal tool was finally determined,having successfully provided a strong evidence for the suspect to convict and sentence.From this case,not only was a technical reference offered for analysis of brake fluid with GC-MS in similar cases but attentions were furthermore suggested to be paid on the role of trace evidence in case analysis and crime scene reconstruction.